Bill Keith is considered by many to be the father of modern chromatic style playing.
He's also the father of the most enduring banjo accessory, the tuner that bears his
name. In the 1960s, Bill and his old Amherst College pal, Dan Bump sat at Bill's
kitchen table with a pair of yellow legal note pads, madly sketching ideas for a
means to eliminate the need for the two bulky additional "cam tuners" which
Earl Scruggs had used to good effect switching from G to D tuning in the middle of
such tunes as "Earl's Breakdown."

Both Dan and Bill had spent long hours working on vintage automobiles with planetary
gear transmissions and drum brakes. They used principles they'd observed in old cars
to come up with the design for their new tuners. Bill had a machine shop at the time,
so he set about actually making the tuners. Since their introduction more than three
decades ago, these tuners have been the industry standard.

Last week, Bill was kind enough to send me an unassembled tuner so I could photograph
the parts and try to understand, then explain exactly how they work. Look these pictures
over, and I think you'll agree that if a product is well enough designed and built,
it simply doesn't need improvement!

Here goes:

Here's the box. If you look at the side, you'll see the name of Bill's
business, the Beacon Banjo Company. Soon, he'll be offering these tuners for sale
on his Web site: www.beaconbanjo.com

And, here's the tuner. As far as I know, it's still the finest piece
of machinery available for a banjo. Machined of solid stainless steel, it's built
solidly, and carries a lifetime warranty. Personally, I've never seen one with a
problem that couldn't be fixed with a few drops of oil.

Inside the shell of this oversized banjo peg is a powerful array of
parts!

The planetary gear drive is the same mechanism used in other banjo
pegs. I'll try to show you how this transmission works in the next few photos.

This is the drive shaft. The end on the right is splined to hold the
button. The end on the left is the small gear that drives the transmission. I'll
talk about that fat section later.

Here, the drive shaft is in place inside the housing, Notice that
the button can be placed on the splined shaft in six different positions.

Let's look at the drive train. You can see the small gear at the end
of the drive shaft in the center. It's called a "sun" gear. Around the
perimeter of is another gear, the "ring gear."

Sitting between the sun gear and the ring gear, three planet gears
"orbit" around the sun gear as the housing is held still and the drive
shaft turns.

The "output" shaft has a little round plate on which the
planet gears are mounted. For this photo, I took the little planet gears out of the
housing and stuck them in place on the output shaft plate.

Going back to the assembled drive, you can see (or imagine) the output
shaft rotating with the round plate as the drive shaft is turned. Because of the
gearing, the output shaft turns once around for every four rotations of the drive
shaft. So, the planet system has a gear ratio of four to one. Jeez, I hope all that
was clear enough, because it gets a bit harder to explain from here.

OK, back to the drive shaft and that fat section.

The fat "tin can" section is actually composed of two major
parts, the clutches which are the stopping mechanisms for the drive shaft. Look closely,
and you can see two pins sticking out of the shaft. Each pin bumps into a raised
semicircular portion of each clutch drum.

This is one of the little clutches up close so you can see the area
where the pins can rotate, stopping against the raised section.

And, here are the three parts that make up the dual clutch system.
At the bottom are the two clutch parts

A little spring sits between the two clutches to keep them separated
when the stops are set.

On the side of the tuner, there are two side screws. Each screw contacts
the edge of one clutch, pining it solidly in place, stopping the rotation of the
drive shaft at a precise location. With both screws set, the tuner will oscillate
between two positions. The side thumbscrews are color coded, black for the high note,
uncolored for the low.

Each thumbscrew has a tiny spring underneath, so that when the screw
is not engaged, there will be a bit of tension on the threads to keep if from vibrating
loose and falling out.

The entire assembly is held together in its housing when the top section
is pressed in and secured by the coarse "knurling" which also serves to
grip the banjo peghead when the peg is installed and screwed down from the top.

Because the third string is raised half a step, and the second string
a full step, the post of the third string tuner is turned to half the diameter of
the second string tuner. That way, each tuner button moves through the same rotation
when they are used to switch from G to D tuning.

On installation, it's customary to rotate the side screws to a position
convenient to the player. Because of the good gripping action of the tuner housing,
it's no problem to reposition them.

To set the tuners, you simply tune to "G" tuning, and lock
the black thumbscrews. Then tune down to "D" and lock the two remaining
thumbscrews. Now, the pegs will go up and down between "G" and "D"
with ease and precision. Once the pegs are set, you can remove the buttons and replace
them on the splined shafts so their position is most convenient for use.